The spiritual leader of the Darkspear tribe, Sen'jin was an enigmatic witch-doctor with a deep and profound link to the spirits and his eternally rain-swept island. Sen'jin lived a relatively peaceful life until new troubles began: Humans from the Kul Tiras marines came to the island and made a settlement, pushing the trolls further into the island. Meanwhile, the once-docile murlocs had become fevered, prodded by the dark Sea Witch that lived in the ocean, who they offered sacrifices to.

Then one night, Sen'jin received a vision...

He saw a young orc— a farseer, who would drive the humans away and save his people, leading them from the island.

That soon came true. As Sen'jin's visions reported, Thrall and his fleet were forced to moor on his island after the Maelstrom nearly destroyed his ships. Sen'jin approached the orcs, warning them of the humans nearby. Thrall promised to force the humans from his island. After defeating an archmage and forcing them into a retreat, they were suddenly attacked by murlocs, who captured Sen'jin's trolls, the witch-doctor himself, as well as Thrall and his people.

Thrall managed to escape the prison and rescued many orcs and trolls, but the murloc high sorcerer took Sen'jin into the deepest part of the underground lair, where he brutally attacked him just as Thrall arrived. Thrall battled through the murlocs and finally destroyed the murloc high sorcerer, but Sen'jin's wounds were deep and he was dying.

In his last breath, Sen'jin implored Thrall to take his people from the island and save them from destruction. To Thrall's surprise, Sen'jin returned to the village a day later.